/Engine/Source/Runtime/Engine/Public/StereoRendering.h
Calculates the offset for the camera position, given the specified position, rotation, and world scale Specifying eSSE_MONOSCOPIC for the view index returns a center offset behind the stereo views
void CalculateStereoViewOffset ( const int32 ViewIndex, FRotator & ViewRotation, const float WorldToMeters, FVector & ViewLocation )